Re: yamaha 90
need to do some very simple tests first, put the lever in neutral, take of the motor cowling and have a look at the adjustments, remove the cable from the lever at the motor end, slowly turn the prop (with your foot, or a helper) and see if the selector moves into reverse ,neutral and forward easily and does it fully engage? from there you should be able to see if it is adjustmenst, cable or something broken.